The invention relates to a novel dentifrice containing glucose oxidase as its essential active ingredient. This enzyme is known as an oxidoreductase, and one of its characteristics is that it forms hydrogen peroxide by oxidative decomposition of its substrate glucose. The action of this enzyme in the dentifrice is twofold: (1) the formation of hydrogen peroxide tends to normalize mouth flora, thus minimizing the generation of acids with concommitant lowering of the pH at the tooth surfaces, and (2) it facilitates the loosening and removal of plaque on the teeth.
Dental caries, or tooth decay, is attributable to several factors. It is well known that as a rule there accumulates on the surface of the teeth a deposit known as plaque, which consists of micro-organisms, proteinaceous and carbohydrate substances, epithelial cells, and food debris. Plaque may be a precursor of calculus, a hard deposit which must be removed mechanically. Plaque may also possibly contribute to various pathological conditions of teeth and to soft tissue in the mouth. The bacteria present in the plaque cause the food products to decay, during which process acids are formed, lowering the pH. Many compounds have been proposed in the patent and other literature for inclusion in dentrifices or mouthwashes to inhibit the formation of plaque or to remove them once formed. Among such compounds are various organic polyphosphonates, p-aminobenzoic acid, benzohydroxamic acid, glutaraldehyde, glyoxylic acid, and many others. None of these appear to have been dependably effective.
As far as pH is concerned, at the surface of the tooth the pH of the saliva is normally about 7.0 to 7.5. Upon the consumption of certain types of foods, particularly those containing sugar, generation of acid takes place, with lowering of the pH down to 5.5 to 4.5, or even lower, a region which is regarded as contributing to tooth decay because under such acid conditions the calcium compounds of the teeth will dissolve in the acid saliva. The time required for restoration of normal pH is a factor of considerable importance, and the more acid the condition of the mouth, the longer this restoration or regeneration period becomes. Dependent upon the nature of the food consumed and the frequency of consumption, the pH can reach varying values, while the time required for the restoration of the normal pH (regeneration time) can also vary greatly. Thus, for example, it has been found that during the consumption of sugars in the form of tough masses, such as toffees, a much lower pH is reached than when these sugars occur in a product with a fibrous structure such as apples, the regeneration time in the first case being moreover much longer.
Further, it has been found that in the repeated consumption of sweets or other products forming acids, the regeneration time gradually increases. Dependent upon the nature of the material the pH can reach values of from 5.5 to 4.5 and sometimes even lower. The zone below the limit of pH about 5.5 is often called the danger zone because under such acid conditions the calcium compounds of the tooth will dissolve in the saliva leading to decay of the tooth. Consequently it will be clear that the lower the pH is and the longer the regeneration time, the greater will be the risk of the teeth being affected.
Besides these two factors there is at least one other factor which plays an important part in tooth decay, i.e. the thickness of the plaque. The fact of the matter is that if the plaque is very thick the acids formed in it by bacterial decomposition have great difficulty in diffusing to the surface, resulting in a lower pH and a longer regeneration period.
In connection with the last-mentioned factor it has been conventional for a considerable time past to incorporate abrasive and/or polishing material in tooth-pastes for the purpose of removing or reducing the plaque, which is the reason why the eating of apples is recommended.
Enzymes are commonly classified according to their mode of action, e.g. hydrolysis, oxidation, or reduction. The hydrolytic enzymes are known as hydrolases, that is, they bring about decomposition of a substrate by the incorporation of water.
It is also known to incorporate enzymes in tooth-pastes and similar dentifrices, e.g. proteases, such as pepsin, pancreatin, trypsin and the like, or amylases. All the enzymes that have been applied so far belong to the group of hydrolases, namely the enzymes which are, among other things, capable of breaking peptide or glycoside bonds in consequence of which macro-molecular compounds are converted into oligomer or monomer products which dissolve more easily in saliva and can thus be removed.